Photoctbaphic light-sensitive matebiax and pbocesb pob itakxng pat



Patented June '17, 1930 I sAMUEL E. snmrnnn AND EUGENE r. ren-rm,

smnonsmo Eurmnxonn: 'rrorz 'OI'INEW Yonxcountr or aocnnsrnn,

or nocnEsrEa, YORK, ns-

nnw roar, A coarom- ,rno"roenarnic imm m mmm m rnoc ssr-on 111mm no Drawing. Application filed February This invention relates to photographic light-sensitivematerials. and to processes of making such materials.

In the manufacture of photographic emul- 3 sions it is known that the colloidal material used contains minute quantities of biochemical ori that have a sulfiding or sulfiding Y and re ucing' action on the silver halides. These materials havevbeen described in the United States Patent,1No. 1,600,736, Punnett, September 21, 1926, and a process istherein given for separating these bodies from the colloidal materiaL' Compounds arelikewise added to photographicfiemulsions to extend the spectrum. 1

' Photographic emulsions, if prepared with added, and often when they contaln only the native sensitizing bodies, have a tendency to fog the light-sensitive materials contained therein. The more powerful the sensitizer, the greater is the tendency to fog. -While such f0 ging action is associated with the \speed 0 the inception of: the latent image, 26 nevertheless, apparent fog must be avoided with its attendant loss in the commercial value of the product.

The object of the present invention is to provide a series of compounds for the purpose of stabilizing light-sensitive materials and thereby correcting the hereinabovedescribed tendencies without markedly retard= 1n rifls} Other objects will hereinafter appear;

We have now found a class of anti-sensitizing or fog-inhibiting compounds which are effective in the production of light sensitive emulsions and in the reparation of col- I loidal intermediates Ifort e manufacture of 40 such emulsions. This new class of substances may be indicated :by the following formula:

' (:CR),or imidnitrogen (:NR).

15 the light-sensitivity far into the red end of the sensitivity of the light-sensitivemate- The photographic sensitivity of silver hal- I thioanalides a class of bodiesof the general formula:

f sensitivity I restraint and fog inhibition is not essential-t0 the ,practical application of ourydiscovery, it exhibits the reasoning by which we were led to it.

Proceeding from these conceptions, we have sought for substances which could com-' bine with the silver halide and particularly at-the boundary of a. growing silver sulphide or other sensitizing speck.

Forexamyop if X and are substituted by H; groupin'gs, there results a compound which is only weakly active in its fog inhibiting or sta 'bi lizing action. .Thesubstitution'of oxygen for H attached to one of the carbon atoms, or, in other words, the substitution of 00 for X and CH tor Y, somewhat increases the eii'ectiveness 'ofthe substance. A more powerful body results when the carbonyl v group issubstitutedafoi" both X and Y. "An

-example,of this type of substance is diacet 1e, in the structure iven above amide, phthalimide, the pyrrol and pyrrol j derivatives suchas succinimide. A: powerv ful to inhibitor or stabilizer is also obtained if car onyl be substituted fornX and a sulfuryl be substituted for Y. In this. case we have'sulfo-ainides and their derivatives, such .for'example as saccharin. I

'There,areother'configurations of the mud group which are also active in respect ottlns inhibitoryaotion on the. fogging of s lver halides. :Itimid' nitrogen replaces the X while .CH,. 'imid-nitrogen, or carbonyl, 'relaces the Y in our above configuration, we have aserie's of compounds which show this activit -The t e pyraz odone ring, an the osotriazo e ring arefexamples of this class'of substances. 1 fIn orde'r'to .thoroughlyand uniformly in- 5 corporate the v non-fogging agent into the I :emulsion'it is usually necessary to dissolve the .material' in asuit'able' solvent such as water or alcohol, or acetone. .Other solvents y or mixturesofthem, of course, may be used 20 that are com atible with the emulsion but we have-found e: above-solvents to be most desirable: I I Theproportionsinwhichthesecompounds are incor orated'in the emulsions, or in the co1loids ibrflthe,v emulsions, are important.

pyrazolone rin pyrazole 6 Too much-of them will often desensltize the emulsion. :Th'e' mairimum proportions which can be used practically vary slightliwith the particularsensitizing compound w ich is selected, with the ratio 'ofgelatin to silver halide in the emulsion, with the t pe of emulsion as regards grain sizean alkalinity, with, the amount of natural sensitizer' also present. in the latin when the latter is man- 'ufactured, wit the particular silver or halides employed, or with the fog standards which are set bythe emulsion manufacture. The optimum proportion is readily obtained by routine test. s

With gelatino silver halide developing-out emulsions, it is generally advantageous to add from .01 to 10 gramsof therestraining substance per 1,000 grams of, gelatine. 'Where gelatine is used in more than one operation,

. as for example in small amounts for precipitation, or in larger amounts at later melt- -ings, these fgelatins -may be differentially treated with the restrainin bodies as will be understood by those skille in the art; 7 5o Our present fog-inhibiting compounds are I effective in all kinds of emulsions ordin in the colloids for the emulsions in the same way asth ose-set forth in UnitcdStates Pat-v exit-No. 1,574,944, March2, 1926. For example, a; mixedjsilver bromide and iodide ly. met with, such as orthochromatic, pane meaeae emulsion in gelatin may prepared as set forth in said-patent,.page 3; After the emulsion is prepared, it may be melted and the 1 roper amount of stabilizing compound thoroughly mixed into it. This mixing is convemently efiectedby dissolving the sta-.-

bilizin substance in a suitable solvent or mixture 0 them, and then stirring such solution into the emulsionu Q 7 7 While our novel sensitizing compounds are preferably used with gelatin, they, never-.

'theless,'have utility with emulsions made in other colloids or agar 1! 'ar, albumins, gums like gum arabic and ce ulose derivatives. Our compounds likewise have utility in emulsions in which different kinds .of silver salts are present suchas silver bromide. I

, tographic emulsion and known equiv ents may be used therefor without in any way departing'from our invention or sacrificing any of the advantages derived therefrom;

Having thus described our invention, what 1 we claim as new and desire to secure by Letters Patent is:

1. A photographic emulsion com rising a colloid, particles of photogra hie a ver salts suspended therein, and an a dad compound in which R is a nitrogen free organic radical and X and Y are selected from activating electro-negative radicals. v

2. A photographic emulsion com rising a colloid, partic es of photogra hic silver salts suspendedtherein, and an a ded compound therein which stabilizes the emulsion and-.on"

, which at least part of the li ht sensitiveness depends, saidcompound bemg of the type in which R 'nitrogen free organic radical and X and are'selected from activatin being solu le ina water miscible solvent.

v and and Y are selected fromthe group comprising the activating electin -negative electro-negjative radicals,v said compoun in which R is anitrogen free organic radical radicals containing sulfur, carbon, and imide nitrogen.

I colloid, partie 'depends, said compound being ofthe type RY NH in which R is a nitrogen free organic radical and X and Y are selected from the group comprising the activating electro negative radicals containing sulfur, carbon, and imide nitrogen, said compound being soluble in a water miyible solvent.

5. A photographic emulsion comprising a colloid, particles of photographic silver salts suspended therein, and an added compound therein which stabilizes the emulsion and on which at least part of the light sensitiveness depends, said compound being of the type R-Y in which R is a nitrogen free organic radical and X and Y are selected from the group of carbonyl, sulfuryl and imid nitrogen, sald compound being soluble in a water misc ble solvent.

6. A photographic emulsion comprising a colloid, particles of photographic silver salts suspended therein, and anadded compound therein which stabilizes the emulsion andon which at least part of the light sensitiveness depends, said compound being of the type R-Y in which R is a-nitrogen free organic radical and X and Y' compriseactivatin electronegative radicals, sald compound orminga closed ring and soluble in a water miscible solvent V l 7, In the process of preparing a develop-. ing-out colloid sensitive silver salt emulsion, 1 stabilizing the light sensitiveness thereofby" incorporating a stabilizing compound therein' in an amount corresponding to .001 to 1% by weight, of the gelatin present, said compound being of the type in which Risa nitrogen free organic radical and X and Y comprise activating electro negative radicals.

8. In 'the process of preparing a. de-

veloping-out \colloi'd sensitive silver salt emulsign, stabilizing the light sensitiveness thereof by incorporating a stabilizing compound thereinin an amount corresponding to .001 to 1% by weight, of the gelatin ,eso -3 present, said compound being of the type NH R-Y in which R is a nitrogen free organic radical and X and Y com rise activating electro-- negative radicals, said compound being soluble in a water miscible solvent.

9. In the process of preparing a develop ng-out colloid sensltive silver salt emulsion, stabilizing the light sensitiveness thereof by incorporating a stabilizing compound therein in an amount corresponding to .001 to 1% by weight, of the gelatin present, said compound being of the type Nn R-Y in which R is a nitrogen free organic radical and X and Y are selected from the group of electro-negative radicals comprising carbonyl, sulfuryl and imide nitrogen.

10. The process of making an inter-. mediate for use in the preparation of photographic emulsions which comprises incorporating in the gelatin .001 to 1% by weight thereof of a stabilizing come pound, said compound being of the type in which Risa nitrogen free organic radical r compound being selected from the group of heterocyclic compounds containing nitrogen in the r1ng and consisting of those compounds containing a -pyrazolone ring,'a pyrazole ring, a pyrazolo'done'ring or an osotriazole.

rmsg. k igned at Rochester, New York this 19th day of February, 1929. SAMUEL E. SHEPPARD. EUGENE P. WIGHTMAN. 

